Docker: Remove traces of direct file access

Change-Id: Id0c11a584a5b75626bb04023893d76fbe2216ade
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/docker/dockerdevice.h

@@ -45,7 +45,6 @@ public:
     QString tag;
     QString size;
     bool useLocalUidGid = true;
-    bool useFilePathMapping = false;
     QStringList mounts;
 };